Hi
@pariahrob
As
@dw1305 mentioned, I've 9 x 50w floods above my 2000L, very similar to the ones you linked. They are aprox 70cm from the substrate.
They can be fantastic value for money, although I couple of things I wish I did different.
Firstly, colour temperature of mine are "cool white", I'd rather something warmer to look at these days (don't think plants care either way)
Secondly, I'd look for ones where there is a single powerful LED, rather than a matrix of smaller ones (such as in your link) IF you're considering it to be open top. The matrix of smaller LEDs spoils the "shimmer" effect you can get if when the light bounces off the waves and fills your room with a feeling of aquatic goodness!
Hope this helps!
Fil